Where is the narrator at the beginning of "The Black Cat" by Edgar Allan Poe?

The answer to this question can be found in a very close
reading of the text, and also in using inference, or an educated guess, to figure out
where he is.  At the beginning of the story, he starts out by addressing the audience
and telling them why he wants to tell his tale:

readability="5.0689655172414">

"But tomorrow I die, and today I
would href="../../black-cat-text/the-black-cat#prestwick-vocab-bes-480">unburthen
my soul."

So, wherever he is,
he knows that tomorrow he is going to die, and he wants to let everyone know what
happened before he does.  This implies that he is possibly in jail, about to be executed
the next day.  Either that, or he is going to kill himself, and wants to share his story
before he does that.  So, given those two alternatives, let's look at what happens to
him at the end of the story that he tells.  He is with the cops, in his house, so
confident of getting away with his crime that he hammers on the walls to show them how
sound they are.  Unfortunately for him, he hammers through the wall and the rotting
corpse of his wife falls out.  From this we can assume that he was arrested--they had
the body right in front of them, so it was pretty solid
proof.

Piecing together what happened at the end, and the
fact that he says he is going to die the next day and so much tell his story, I would
guess that he is in prison, about to be executed for the crime of murdering his wife. 
His story is his last confession before he dies.  I hope that those thoughts helped;
good luck!